<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>learn selenium</title>
    <script type="text/javascript">
        function display_alert(){
            alert("人间向晚")
        }
    </script>
</head>
<body>
<input type="button" onclick="display_alert()" value="点击">
</body>
</html>